Window-envelop.



C. J. GUTBERLET.

WINDOW ENVELOP.

APPLICATION FILED JULY'5. 1911.

Patented Oct. 30, 1917.

Fig. 5

a Fig. 5.

CHARLES J. GUTBERLET, OF PHILADELPHIA, PENNSYLVANIA.

WINDOW-ENVELOP.

Application filed July 5, 1917.

To all whom it may concern:

Be it known that I, CHARLES J. GUTBER- LET, a citizen of the UnitedStates, residing at Philadelphia, in the county of Philadelphia andState of Pennsylvania, have invented certain new and useful Improvementsin lVindow-Envelops, of which the following is a specification.

The present device has the window integral with and at or below thelevel of the body of the envelop and by the construction of the window,it is supported by and integral with a frame of sturdy paper, so thatthe ordinary paper of envelop manufacture can be used, and the windownevertheless can be made completely transparent without taking away fromthe envelop its necessary strength on the window face. The envelop isalso without any obstruction to the insertion of the inclosure, which isimportant notonly because of the inconvenience produced by anyobstruction in inserting the inclosure, but also because the window maybe torn by the effort to insert the inclosure forcibly against anobstruction. The process by which the envelop is manufactured is alsovery simple and efficient.

Figure 1 is an elevation showing the face of the envelop, Fig. 2 is aside section on the line wa2 of Fig. 1. Fig. 8 is a greatly enlargedsectional view of the portions of the face of the envelop having theframe and the window. Fig. 4 is a like view showing a slightly modifiedform of the window and frame, and Fig. 5 is a plan view of theinstrument for treating the window to render same transparent.

The envelop may be of any suitable paper stock and shape. It is shown inthe conventional form with face 2, sealing flap 1 and back flaps 4 and5. The window 3 is located where the address would ordinarily be placedon the envelop. This window is much thinner than the rest of the envelopand its surfaces both inside and outside the envelop are highlypolished. It is integral with the frame and depressed (as shown in Figs.2- and 3) below the surface of the frame on the inside as well as theoutside of the envelop. The faces of the window are parallel planes,which is important as the window should be of equal strength throughout,and, besides, the making of these surfaces parallel planes addsmaterially to the windows transparenty. The window is Specification ofLetters Patent.

Patented Oct. 30, 1917.

Serial No. 179,977. Y

joined to the frame with sloping shoulders {land 7, which give strengthand make the inclosure slip in easily and the face of the envelop slipeasily over another envelop.

Transparency is given to the window by treating it with a transparentfiller and then preferably polishing the surfaces. The filler is of aglutinous as well as oily nature so that a rigidity and strength isgiven to the window much greater than would be given by merely the paperfiber itself. This filler is carried all the way to the shoulders andover them. The best material is a heavy white mineral oil with aparafiin base. If the thinning of the paper fiber to form the window andthe additional stiffening and strengthening given by the filler areproperly balanced, the whole face of the envelop, including the windowwill have an equal strength and rigidity throughout. In Fig. 4. is showna form where the thinning of the paper to form the window is only on oneside of the face of the envelop. 12 is the portion of the face of theenvelop, 16 and 17 the shoulders and 13 the-window.

The process of producing this envelop is as follows :The blank has thewindow skived or ground out, which can be done by automatic machinery orby a revolving cutter of very fine emery or carrying revolving knives oreven by skiving it out, and the window is then treated with the fillerby dipping into the latter the stamp shown in Fig. 5, the plate 14 ofwhich is preferably made of a. porous material such as sandstone. Theface of this stamp should fit exactly the window shape so that it willregister with it and cover it but not extend over the frame. This stamp,when the making of the window is not done by automatic ma- 'chinery isdipped into the filler and taken by the handle 15 and pressed upon thewindow of the blank. The blank is then allowed to dry. Either before orafter the application of the filler the surface of window is polished.

I claim l. A window envelop, having the window formed of the paperconstituting the face of the envelop but thinner than the rest of theenvelop face and integral therewith, the opposite surfaces of the windowbeing parallel planes and polished, and said window having shouldersconnecting the same with the face of the envelop, formed of paperintegral with the window and the envelop face, and having the Window upto the Ehoulders filled with a transparent tenacious ller.

2. A WlIldOW' envelop, having the-WindoW formed of the paperconstituting the face of the envelop but thinner than the rest of theenvelop face and integral therewith, the 0pposite surfaces of the Windowbeing parallel planes and polished and integral therewith, and saidWindow having shoulders connecting the same with face of the envelop,formed of paper integral With the Window and the envelop face, andhaving the Window up to the shoulders filled with a heavy oil with aparaflin base. i

3. The art of making Window envclops,

Which consists in subjecting the blank to a CHAS. J. GUTBE RLET.

